Inactivation of ku80 in the mushroom-forming fungus Schizophyllum commune increases the relative incidence of homologous recombination.

Schizophyllum commune is the only mushroom-forming fungus in which targeted gene deletions by homologous recombination have been reported. However, these deletions occur with a low frequency. To overcome this, the ku80 gene of S. commune was deleted. This gene is involved in the nonhomologous end-joining system for DNA repair. The Deltaku80 strain was not affected in growth and development. However, the transformation efficiency was reduced up to 100-fold. This was accompanied by a strong increase in the relative number of transformants with a homologous integration of a knockout construct. Genes sc15, jmj3 and pri2 were deleted in the Deltaku80 strain. In total, seven out of 10 transformants showed a gene deletion. This frequency will facilitate a systematic analysis of gene function in S. commune.